# The Use of Non-Invasive Brain Stimulation Techniques in Subjects with Parkinson’s Disease and Mild Cognitive Impairment: A Systematic Review

## TL;DR

Non-invasive brain stimulation may help improve memory and cognition in Parkinson’s disease patients with mild cognitive impairment, but more research is needed.

## Contribution

This systematic review identifies NIBS as a potential non-pharmacological therapy for PD-MCI with specific cognitive benefits.

## Key findings

- Intermittent theta burst stimulation and transcranial direct current stimulation improved episodic memory and global cognition in PD-MCI patients.
- Cognitive improvements were better detected using sensitive tools like Montreal Cognitive Assessment and Repeatable Battery for the Assessment of Neuropsychological Status.
- Future trials should combine NIBS with cognitive training and include medium-term follow-ups to assess neuroplastic effects.

## Abstract

What are the main findings?
•Non-invasive brain stimulation (NIBS), particularly intermittent theta burst stimulation and transcranial direct current stimulation targeting the dorsolateral prefrontal cortex, shows some efficacy in improving episodic memory and global cognition in patients with Parkinson’s disease (PD) and mild cognitive impairment (MCI).•The detection of cognitive improvement is highly dependent on the sensitivity of assessment tools, with the Montreal Cognitive Assessment and the Repeatable Battery for the Assessment of Neuropsychological Status having superior results compared to tests of global cognition such as the Mini-Mental State Examination.

Non-invasive brain stimulation (NIBS), particularly intermittent theta burst stimulation and transcranial direct current stimulation targeting the dorsolateral prefrontal cortex, shows some efficacy in improving episodic memory and global cognition in patients with Parkinson’s disease (PD) and mild cognitive impairment (MCI).

The detection of cognitive improvement is highly dependent on the sensitivity of assessment tools, with the Montreal Cognitive Assessment and the Repeatable Battery for the Assessment of Neuropsychological Status having superior results compared to tests of global cognition such as the Mini-Mental State Examination.

What are the implications of the main findings?
•NIBS represents a promising non-pharmacological add-on therapy for specific cognitive deficits in PD.•Future clinical trials should prioritize combined interventions (stimulation plus cognitive training) and include medium-term follow-up to capture delayed neuroplastic effects on executive functions.

NIBS represents a promising non-pharmacological add-on therapy for specific cognitive deficits in PD.

Future clinical trials should prioritize combined interventions (stimulation plus cognitive training) and include medium-term follow-up to capture delayed neuroplastic effects on executive functions.

Background/Objectives: Mild cognitive impairment (MCI) is common in Parkinson’s disease (PD) and significantly impacts quality of life. Non-invasive brain stimulation (NIBS) techniques have emerged as potential therapeutic interventions. This systematic review analyzes the current evidence regarding the efficacy of Transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (tES) on cognitive domains in patients with PD-MCI. Methods: A systematic search was conducted across the PubMed, Scopus, Web of Science, and Medline Ultimate databases up to 20 November 2025. We included studies investigating the effects of NIBS compared to sham stimulation on neuropsychological outcomes in diagnosed PD-MCI patients. Results: Eight studies involving different stimulation protocols were included. Interventions primarily used TMS or tES targeting the left dorsolateral prefrontal cortex (DLPFC). Episodic memory and global cognition were the most responsive domains, assessed with specific neuropsychological scales. Findings for executive functions and attention were heterogeneous, while visuospatial abilities generally showed limited immediate response. Conclusions: NIBS represents a promising but low-certainty-evidence adjunctive therapy for PD-MCI, with improvements found in memory and global cognition. Future research should prioritize larger sample sizes, combined interventions (NIBS plus cognitive rehabilitation), and extended follow-ups to evaluate long-term neuroplasticity.